(function () {
  /**
   * Description: A THREE loader for STL ASCII files, as created by Solidworks and other CAD programs.
   *
   * Supports both binary and ASCII encoded files, with automatic detection of type.
   *
   * The loader returns a non-indexed buffer geometry.
   *
   * Limitations:
   *  Binary decoding supports "Magics" color format (http://en.wikipedia.org/wiki/STL_(file_format)#Color_in_binary_STL).
   *  There is perhaps some question as to how valid it is to always assume little-endian-ness.
   *  ASCII decoding assumes file is UTF-8.
   *
   * Usage:
   *  const loader = new STLLoader();
   *  loader.load( './models/stl/slotted_disk.stl', function ( geometry ) {
   *    scene.add( new THREE.Mesh( geometry ) );
   *  });
   *
   * For binary STLs geometry might contain colors for vertices. To use it:
   *  // use the same code to load STL as above
   *  if (geometry.hasColors) {
   *    material = new THREE.MeshPhongMaterial({ opacity: geometry.alpha, vertexColors: true });
   *  } else { .... }
   *  const mesh = new THREE.Mesh( geometry, material );
   *
   * For ASCII STLs containing multiple solids, each solid is assigned to a different group.
   * Groups can be used to assign a different color by defining an array of materials with the same length of
   * geometry.groups and passing it to the Mesh constructor:
   *
   * const mesh = new THREE.Mesh( geometry, material );
   *
   * For example:
   *
   *  const materials = [];
   *  const nGeometryGroups = geometry.groups.length;
   *
   *  const colorMap = ...; // Some logic to index colors.
   *
   *  for (let i = 0; i < nGeometryGroups; i++) {
   *
   *		const material = new THREE.MeshPhongMaterial({
   *			color: colorMap[i],
   *			wireframe: false
   *		});
   *
   *  }
   *
   *  materials.push(material);
   *  const mesh = new THREE.Mesh(geometry, materials);
   */

  class STLLoader extends THREE.Loader {
    constructor(manager) {
      super(manager);
    }

    load(url, onLoad, onProgress, onError) {
      const scope = this;

      const loader = new THREE.FileLoader(this.manager);
      loader.setPath(this.path);
      loader.setResponseType("arraybuffer");
      loader.setRequestHeader(this.requestHeader);
      loader.setWithCredentials(this.withCredentials);

      loader.load(
        url,
        function (text) {
          try {
            onLoad(scope.parse(text));
          } catch (e) {
            if (onError) {
              onError(e);
            } else {
              console.error(e);
            }

            scope.manager.itemError(url);
          }
        },
        onProgress,
        onError
      );
    }

    parse(data) {
      function isBinary(data) {
        const reader = new DataView(data);
        const face_size = (32 / 8) * 3 + (32 / 8) * 3 * 3 + 16 / 8;
        const n_faces = reader.getUint32(80, true);
        const expect = 80 + 32 / 8 + n_faces * face_size;

        if (expect === reader.byteLength) {
          return true;
        }

        // An ASCII STL data must begin with 'solid ' as the first six bytes.
        // However, ASCII STLs lacking the SPACE after the 'd' are known to be
        // plentiful.  So, check the first 5 bytes for 'solid'.

        // Several encodings, such as UTF-8, precede the text with up to 5 bytes:
        // https://en.wikipedia.org/wiki/Byte_order_mark#Byte_order_marks_by_encoding
        // Search for "solid" to start anywhere after those prefixes.

        // US-ASCII ordinal values for 's', 'o', 'l', 'i', 'd'

        const solid = [115, 111, 108, 105, 100];

        for (let off = 0; off < 5; off++) {
          // If "solid" text is matched to the current offset, declare it to be an ASCII STL.

          if (matchDataViewAt(solid, reader, off)) return false;
        }

        // Couldn't find "solid" text at the beginning; it is binary STL.

        return true;
      }

      function matchDataViewAt(query, reader, offset) {
        // Check if each byte in query matches the corresponding byte from the current offset

        for (let i = 0, il = query.length; i < il; i++) {
          if (query[i] !== reader.getUint8(offset + i)) return false;
        }

        return true;
      }

      function parseBinary(data) {
        const reader = new DataView(data);
        const faces = reader.getUint32(80, true);

        let r,
          g,
          b,
          hasColors = false,
          colors;
        let defaultR, defaultG, defaultB, alpha;

        // process STL header
        // check for default color in header ("COLOR=rgba" sequence).

        for (let index = 0; index < 80 - 10; index++) {
          if (
            reader.getUint32(index, false) == 0x434f4c4f /*COLO*/ &&
            reader.getUint8(index + 4) == 0x52 /*'R'*/ &&
            reader.getUint8(index + 5) == 0x3d /*'='*/
          ) {
            hasColors = true;
            colors = new Float32Array(faces * 3 * 3);

            defaultR = reader.getUint8(index + 6) / 255;
            defaultG = reader.getUint8(index + 7) / 255;
            defaultB = reader.getUint8(index + 8) / 255;
            alpha = reader.getUint8(index + 9) / 255;
          }
        }

        const dataOffset = 84;
        const faceLength = 12 * 4 + 2;

        const geometry = new THREE.BufferGeometry();

        const vertices = new Float32Array(faces * 3 * 3);
        const normals = new Float32Array(faces * 3 * 3);

        for (let face = 0; face < faces; face++) {
          const start = dataOffset + face * faceLength;
          const normalX = reader.getFloat32(start, true);
          const normalY = reader.getFloat32(start + 4, true);
          const normalZ = reader.getFloat32(start + 8, true);

          if (hasColors) {
            const packedColor = reader.getUint16(start + 48, true);

            if ((packedColor & 0x8000) === 0) {
              // facet has its own unique color

              r = (packedColor & 0x1f) / 31;
              g = ((packedColor >> 5) & 0x1f) / 31;
              b = ((packedColor >> 10) & 0x1f) / 31;
            } else {
              r = defaultR;
              g = defaultG;
              b = defaultB;
            }
          }

          for (let i = 1; i <= 3; i++) {
            const vertexstart = start + i * 12;
            const componentIdx = face * 3 * 3 + (i - 1) * 3;

            vertices[componentIdx] = reader.getFloat32(vertexstart, true);
            vertices[componentIdx + 1] = reader.getFloat32(vertexstart + 4, true);
            vertices[componentIdx + 2] = reader.getFloat32(vertexstart + 8, true);

            normals[componentIdx] = normalX;
            normals[componentIdx + 1] = normalY;
            normals[componentIdx + 2] = normalZ;

            if (hasColors) {
              colors[componentIdx] = r;
              colors[componentIdx + 1] = g;
              colors[componentIdx + 2] = b;
            }
          }
        }

        geometry.setAttribute("position", new THREE.BufferAttribute(vertices, 3));
        geometry.setAttribute("normal", new THREE.BufferAttribute(normals, 3));

        if (hasColors) {
          geometry.setAttribute("color", new THREE.BufferAttribute(colors, 3));
          geometry.hasColors = true;
          geometry.alpha = alpha;
        }

        return geometry;
      }

      function parseASCII(data) {
        const geometry = new THREE.BufferGeometry();
        const patternSolid = /solid([\s\S]*?)endsolid/g;
        const patternFace = /facet([\s\S]*?)endfacet/g;
        let faceCounter = 0;

        const patternFloat = /[\s]+([+-]?(?:\d*)(?:\.\d*)?(?:[eE][+-]?\d+)?)/.source;
        const patternVertex = new RegExp("vertex" + patternFloat + patternFloat + patternFloat, "g");
        const patternNormal = new RegExp("normal" + patternFloat + patternFloat + patternFloat, "g");

        const vertices = [];
        const normals = [];

        const normal = new THREE.Vector3();

        let result;

        let groupCount = 0;
        let startVertex = 0;
        let endVertex = 0;

        while ((result = patternSolid.exec(data)) !== null) {
          startVertex = endVertex;

          const solid = result[0];

          while ((result = patternFace.exec(solid)) !== null) {
            let vertexCountPerFace = 0;
            let normalCountPerFace = 0;

            const text = result[0];

            while ((result = patternNormal.exec(text)) !== null) {
              normal.x = parseFloat(result[1]);
              normal.y = parseFloat(result[2]);
              normal.z = parseFloat(result[3]);
              normalCountPerFace++;
            }

            while ((result = patternVertex.exec(text)) !== null) {
              vertices.push(parseFloat(result[1]), parseFloat(result[2]), parseFloat(result[3]));
              normals.push(normal.x, normal.y, normal.z);
              vertexCountPerFace++;
              endVertex++;
            }

            // every face have to own ONE valid normal

            if (normalCountPerFace !== 1) {
              console.error("THREE.STLLoader: Something isn't right with the normal of face number " + faceCounter);
            }

            // each face have to own THREE valid vertices

            if (vertexCountPerFace !== 3) {
              console.error("THREE.STLLoader: Something isn't right with the vertices of face number " + faceCounter);
            }

            faceCounter++;
          }

          const start = startVertex;
          const count = endVertex - startVertex;

          geometry.addGroup(start, count, groupCount);
          groupCount++;
        }

        geometry.setAttribute("position", new THREE.Float32BufferAttribute(vertices, 3));
        geometry.setAttribute("normal", new THREE.Float32BufferAttribute(normals, 3));

        return geometry;
      }

      function ensureString(buffer) {
        if (typeof buffer !== "string") {
          return new TextDecoder().decode(buffer);
        }

        return buffer;
      }

      function ensureBinary(buffer) {
        if (typeof buffer === "string") {
          const array_buffer = new Uint8Array(buffer.length);
          for (let i = 0; i < buffer.length; i++) {
            array_buffer[i] = buffer.charCodeAt(i) & 0xff; // implicitly assumes little-endian
          }

          return array_buffer.buffer || array_buffer;
        } else {
          return buffer;
        }
      }

      // start

      const binData = ensureBinary(data);

      return isBinary(binData) ? parseBinary(binData) : parseASCII(ensureString(data));
    }
  }

  THREE.STLLoader = STLLoader;
})();
